Why Does Toilet Water Move When It's Windy Outside?

iStock/kanjana intaounwong
iStock/kanjana intaounwong

Reader Erin from Baltimore wrote in wondering why the water in her toilet bowl moves on windy days. This is one of those questions – like the one Jason asked about his dog’s popcorn-scented paws – that makes me pause and wonder if I’m getting trolled, or if I’m missing out on a strange phenomena that everyone else seems to be aware of.

So, I did a little Googling and even hung out in the bathroom staring at the toilet bowl one morning (yes, folks, this is the exciting life of a science writer). Turns out Erin isn’t messing with me. Perhaps I'm one of the last people on Earth to realize toilet water moves with the breeze. Way to go, Soniak.

So, what causes this commotion in the latrine?

In many homes (at least in the U.S.), part of the plumbing system is a pipe that runs up and out to the roof. This outlet, called a “vent stack,” allows sewage gases to vent outside instead of through the toilet, sink or tub—which would make the house reek. The stack also allows air to move through the pipes, which makes wastewater drain smoothly and keeps obnoxious gurgling to a minimum.

When the wind blows over the vent stack outlet on the roof, the air pressure in the pipe is lowered. This is Bernoulli’s principle (“as the speed of a moving fluid increases, the pressure within the fluid decreases”), the same thing that gives airplanes their lift, in action in your bathroom. The lowered pressure in the pipes creates a slight suction effect throughout the plumbing system, pulling on water in the toilet below. As the wind kicks up and dies down, the suction gets stronger and weaker, and the water in the bowl sloshes around accordingly.

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What Really Happens When Food Goes Down the 'Wrong Pipe'?

The dreaded 'wrong pipe' calamity can strike at any time.
The dreaded 'wrong pipe' calamity can strike at any time.
Photo by Adrienn from Pexels

Your average person isn’t expected to be well-versed in the linguistics of human anatomy, which is how we wind up with guns for biceps and noggins for heads. So when swallowing something is followed by throat irritation or coughing, the fleeting bit of discomfort is often described as food “going down the wrong pipe.” But what’s actually happening?

When food is consumed, HuffPost reports, more than 30 muscles activate to facilitate chewing and swallowing. When the food is ready to leave your tongue and head down to your stomach, it’s poised near the ends of two "pipes," the esophagus and the trachea. You want the food to take the esophageal route, which leads to the stomach. Your body knows this, which is why the voice box and epiglottis shift to close off the trachea, the “wrong pipe” of ingestion.

Since we don’t typically hold our breath when we eat, food can occasionally take a wrong turn into the trachea, an unpleasant scenario known as aspiration, which triggers an adrenaline response and provokes coughing and discomfort. Dislodging the food usually eases the sensation, but if it’s enough to become stuck, you have an obstructed airway and can now be officially said to be choking.

The “wrong pipe” can also be a result of eating while tired or otherwise distracted or the result of a mechanical problem owing to illness or injury.

You might also notice that this happens more often with liquids. A sip of water may provoke a coughing attack. That’s because liquids move much more quickly, giving the body less time to react.

In extreme cases, food or liquids headed in the “wrong” direction can wind up in the lungs and cause pneumonia. Fortunately, that’s uncommon, and coughing tends to get the food moving back into the esophagus.

The best way to minimize the chances of getting food stuck is to avoid talking with your mouth full—yes, your parents were right—and thoroughly chew sensible portions.

If you experience repeated bouts of aspiration, it’s possible an underlying swallowing disorder or neurological problem is to blame. An X-ray or other tests can help diagnose the issue.

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